1. Field of the Invention
The present invention relates to data transmission using a Universal Serial Bus (USB) port, and more particularly to an apparatus and a method for sharing an USB port and transmitting data in a hybrid terminal including two Central Processing Units (CPUs) and memories corresponding to the two CPUs.
2. Description of the Related Art
With the popularization of mobile communication terminals and the various demands of users, mobile communication terminals have come to include various supplementary functions in addition to a basic communication function. For example, the supplementary functions may include various functions such as a camera function, a play function of a music file including a Moving Picture experts group layer 3 (MP3), a dynamic image play function, a position tracking function associated with a Global Positioning System (GPS), and a Personal Digital Assistant (PDA). A mobile communication terminal including the supplementary functions has two CPUs. In a mobile communication terminal (hybrid terminal) usually including two CPUs, one CPU controls a series of operations relating to wireless communication, and the other CPU controls a series of operations relating to the supplementary functions in addition to wireless communication. Further, the hybrid terminal includes memories corresponding to each CPU and supports control operations of each CPU.
In the meantime, as mobile communication terminals are constructed so as to exchange USB data with an external apparatus, the mobile communication terminals include USB ports, USB input/output units, and USB Mass Storages (UMSs). If such a mobile communication terminal is connected to a computer, etc., through a USB data transmission cable, the computer recognizes a memory included in the mobile communication terminal as a removable disk, and transmits data to the mobile communication terminal or reads data stored in the mobile communication terminal. Such a USB function allows a user to easily download data relating to functions of the mobile communication terminal and to use the memory of the mobile communication terminal as a removable disk.
However, because a mobile communication terminal is manufactured in a small size in order to ensure portability, it usually has only one USB port. Likewise, the hybrid terminal also has only one USB port. Accordingly, in the case of the hybrid terminal, one of two CPUs can perform data transmission/reception through the USB port, but the other CPU cannot use the USB port. Even when each of the two CPUs support a USB function, the two CPUs cannot perform the USB function because the hybrid terminal does not have two USB ports due to its small size, which is required for portability. Therefore, in the case of the hybrid terminal, a memory of a CPU, which cannot perform USB data communication due to non-assignment of a USB port, has a low degree of utilization, as compared with a memory of the CPU which can perform USB data communication through connection of the USB port. In other words, the overall efficiency of using the memory of the hybrid terminal may deteriorate.